MIT class designs 82,000-square-foot mass timber prototype

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Dive Brief:

In an effort to come up with a feasible and safe large-scale, energy-efficient mass timber structure, a class at the Massachusetts Institute of Technology has designed and submitted for presentation at the Maine Mass Timber Conference in October an 82,000-square-foot prototype community building called the Longhouse, according to the MIT News.

The building's structural design consists of beams comprised of 50-foot by 10-foot by six-inch laminated veneer lumber panels, which are made of layers of wood veneers joined by adhesives. The panels are then cut to size in order to create 40-foot-tall, 50-foot-wide arches that are strengthened with triangular cross sections and used for the structural bones of the building. The specifications for construction, if the structure is ever built, provide for offsite prefabrication and onsite assembly.

One of the most formidable obstacles facing the wider use of mass timber products in high-rises and other large structures in the U.S. is the country's systems of building codes. Typically, building codes limit the use of structural wood components in residential construction to five stories and in commercial construction to six stories. Some developers building high-rise wood structures have received exemptions to these rules, and, according to John Klein, a research scientist in MIT’s architecture department and leader of the class that came up with the Longhouse design, the more tall wood structures that can be built and safely occupied, the better the chances are that building codes will eventually change.

Dive Insight:

Another concern that has hindered mass timber efforts in the U.S. and elsewhere is that of fire safety. However, the heavy timber used in modern wood structures will typically char when exposed to fire, creating a flame resistant protective layer that preserves up to 90% of the wood's strength.

Mass timber advocates won a victory earlier this year when Washington Gov. Jay Inslee signed a law requiring state building code officials to start developing rules for the use of mass timber in commercial and residential construction up to 18 stories. Some lawmakers in timber-rich Washington state are also pushing for legislation that would require mass timber to be used in buildings of 12 stories or less.

Minnesota is also exploring what it's going to take to enter the mass timber industry and is in the process of surveying the state's sawmills to determine if the state has the capacity to launch such an initiative, according to Forum News Service.